IL29940A - Composite filaments - Google Patents

Description

Composite filaments GLANZSTOPF A. .

This invention relates to composite filaments consisting of two polymers with different shrinkages.

The term composite filaments as used herein is taken to mean monofilar and multifilar filaments which are produced in a known manner by spinning two different spinning compositions from special nozzles or spinnerets. Devices in such spinnerets make it possible for two polymer solutions or melts to be extruded from one spinneret aperture to form core-sheathed filaments, or filaments in which both polymers form a part of the filament surface and of the filament cross-section.

Composite filaments which undergo crimping immediately after being spun and stretched, without any special treatment or under the action of water or steam have become very important. In producing such composite filaments, polymers are used which have different physical and/or chemical properties, particularly those having different shrinkages. Crimping always occurs if both polymers form at least a part of the surface or, with eccentric formation, a part of a core-sheath structure.

One knownprocess relates to the production of composite filaments from two polymers having highly differing shrinkages. In this process, the component with the larger shrinkage must have a shrinkage of at least 5 7% and the difference in the shrinkages of the two components should be at least 10 preferably 20%, Examples of suitable polymer combinations are polyamides formed from dicarboxylic acids and diamines or from capro- lactam and polyethylene terephthalate..

One of the components can also be a copolyamide or copolyester.

Composite filaments which are produced by the known process, using different polymer combinations, tend to crimp after heat treatment, the extent of the crimping depending on the nature and quantity of the composition. For example, a core-sheath fila-ment with an eccentric formation of core and sheath, consisting of polyamide and polyethylene terephthalate, after being treated with water at 95eC, exhibits a -crimping factor of 115 per 10 cm of filament length.

Accordingly the invention provides a composite filament of two polymers with different shrinkages and having an eccentric formation of core and sheath, in which the sheath of the filament is a homopolyamide and the core a copolyetheramide, which has been produced by polycondensation of adipic acid with 75 to 20 raol%, of an ether diamine of the formula H2 - (CH2)3 - R - (CH2)3 - H2 in which R can represent the groups -0- or -0- (CH2)n -0- and in which n is 2 to 4» and 25 to 80 mol %, of hexamethylene diamine. It is preferred to use 0 to 40 mol °/o of the ether diamine and 50 to 60 mol hexamethylene diamine.

The proportions by weight between sheath and core of the composite filament according to the invention should be between 30 : 70 to 70 : 30, preferably 50 i 50 The composite filaments produced according to > f the invention have much better properties than those previously known, particularly in their crimping behaviour.

The known homopolyamides , for example, those formed from caprolactam, hexamethylene diamine and adipic acid and amino-undecanic acid are suitable for use as sheath components in the composite filaments according to the invention.

Those composite filaments in which the sheath consists of polyhexamethylene adipamide or polycapro- lactam and in which the core consists of the copolyether amide, which has been prepared by polycondensation of adipic acid with 40 mol of ether diamine of the formula H2 -(CH2)3 - 0 - (CH2)2 - 0 - (CH2)3 - NH2 and 60 mol% of hexamethylene diamine are preferred.

Copolyether amides of this composition are prepared in accordance with German Patent Specification Application Serial No. G 47 , 579 IVd/39c ) . According to the process described there, any arbitrary ratio of Hther diamine to hexamethylene diamine can be used to produce copolyether amides which have a sufficiently high molecular weight and good filament-forming properties These copolyether amides have a surprisingly high shrinkage.

The shrinkage values of some copolyether amide filaments and other polymer filaments in water at 95°C and ° C are given in Table I.

Table I Filament material Shrinkage at 95°C 20°C copolyether amide of adipic acid and hexamethylene diamine and ether diamine + 50 mol% 50 molfo 60% 35% i+O mol% 60 " 50% 20 " 70 " 38 14% polyamide of caprolactam 11% 6.2% polyamide of adipic acid and hexamethylene diamine 7^% 5.4% copolyamide of SO mol% caprolactam and 20 mol% adipic acid-bexamethylene diamine 35-40 9.8% + The ether diamine is of the formula: H2 - (CH2)3 - 0 - (CH2)2 - 0 - (CH2)3 - H2 The table shows that the shrinkability of the copolyether amide filament with the smallest degree of shrinkage in water at 95°C still has a similar shrinkage to the said copolyamide, whereas the copolyether amide with the highest shrinkage has almost the same shrinkage in water at 20°C. As it is mainly the difference in the shrinkage of the two polymer components which governs the crimping properties of the composite filaments, the advantages of the invention are obvious.

The composite filaments according to the invention are produced by known melt spinning methods; the spinning temperature used is that normally used for the melt spinning of the homopolyamide used as the sheath component. The spinning process and the stretching are carried out under the usual processing conditions.

One particular advantage of the composite filaments according to the invention is that they will undergo crimping on being dipped in water at room temperature.

When compared with composite filaments of known type, in which the core consists, for example, of polyethylene terephthalate and the sheath of a poly- 10 amide, the filaments according to the invention have the advantage that the core and sheath remain firmly bonded to each other, because of the greater chemical similarity of the components.

The production of composite filaments according to the invention is illustrated by the following example: Using a spinneret , which is suitable forthe production of core-sheath composite filaments with an eccentric formation of core and sheath, a melt of a homopolyamide (as the sheath) and a melt of the copo- 20 lyether amide of adipic acid, hexamethylene diamine and ether diamine of the formula H2 - (CH2)3 - 0 - (C¾)2 - 0 - (<¾).-. - H2 (as the core) are spun. The temperature of the spinning 2^ apparatus is about 2#0°C, The filament is withdrawn at. a speed of 750 m/min from the spinneret, after which it is cold-stretched in the ratio 1 : 3·5 an reeled. Table II shows the textile data of composite filaments according to the invention using different compositions of the copolyether amide and also different core and sheath proportions , Corres ponding data of known composite filaments are given for comparison. sheath ate poly- . copoly- filaamide ether ments II amide A 50:50 .40/ 0- 37.5 5.9 18% . 7.

' -It • B 50:50 II 28.0 2.7 10 5.

II C 50:50 II 35. 2.9 13% . . 5.

II A 70:30 II 40.0 4.0 : 16% 7.

It A 50:70 ti 34.4 3.2 26% 11. polyamide A 50:50 »· 33.5 2.9 16% 6. polycopoly-, II amide 1) amide J 50:5Ο: 30.6 3. 15 5. polypoly- amide 1) ethylane 50:50 II 36.8 4.6 17% . 1. tere- phthalate 1) Polyamide of caprolactam 2) Polyamide of adipic acid and hexamethylene diamine 3) Copolyamide of caprolactam and adipic acid-hexamethylene diamine in the A) Copolyether amide of adipic acid-hexamethylene diamine and ether diamin B) "n II It . it it 11 11 C) II Π It 11 it » » The following methods were used to measure these quantities, after the crimping had been initiated by treatment with water at 95°C for 2 minutes. 1) Crimping elongation A piece of filament about 1 metre long, after this treatment, is then subjected to a load of 50 mg/den, so that the crimping is largely removed. The stretched filament is fixed to the upper edge of a wall which is disposed at a slight inclination. A smaller weight of 0.5 mg/den is then clipped to the filament just above the said weight and the larger weight is then carefully removed. The filament is conditions left for 12 hours under this load under normal/of temperature and humidity. After this time, the fila-15 ment is clamped with the hanging weight in an electronic tensile strength tester and the elongation with the loading of 0.05p/den is determined. 2) Crimping contraction Small filament skeins {& m long) are wound and these 20 are hung for 30 seconds without tension in distilled water at a temperature of 70° C. The wet skeins are then loaded for 1 minute with weights of 0,2 g/den. The length obtained under this load is designated as b.

After removing the weights, the skeins are dried while 25 hanging freely without load for 30 minutes at 50-60°C and are thereafter air-conditioned for 1 hour. They are then loaded for 1 minute with a weight of 0.002 g/den. The length established is designated as a.

The crimping contraction is calculated in accordance with the equation, % crimping contraction = ^ a x 100 The diagrams, in the accompanying drawings show the crimping elongations of different composite filaments plotted against the shrinkability (Fig 1) and the loading (Fig 2). The curves show the crimping elongation of composite filaments of the following composition: Curves a and a-. = polycaprolactam and copolyether amide A (for explanation, see beneath Table II) Curves b and b-, β polycaprolactam and copolyamide (of 80% caprolactam and 20 hexamethylene diamine-adipic acid) Curves c and c-, = polycaprolactam and polyethylene terephthalate.

In each case the sheath of the filament consists of the first polymer and the core of the second compound. The quantitative ratio between sheath and core is 50:50 and the filament count is 0 den (10 separate filaments).

To obtain the crimping elongation values for Fig.l, the filaments were clamped in a frame with a clip . spacing of 30 cm so that different shrinkabilities could be obtained. With a 10% shrinkability, the clamped filament length was 33 cm. and with B0% shrinkability 54 cm. The filaments secured in this way were firstly boiled for 60 minutes in water, then dried for 60 minutes in hot air (60°C) and finally set for 3 minutes at 115°C in saturated steam. The determination of the crimping elongation was carried out as before except that the length of the measured pieces of filament was only 30 cm.

The crimping elongation values which are shown in Figure 2 were established after the filaments had been treated in water at 95° C for 2 minutes, under the loads indicated in the diagram.

It is apparent from both diagrams that the composite filament according to the invention shows the most favourable crimping properties.

Claims (7)

WHAT WE CLAIi

1. A composite filament of two polymers with diff-eronfc shrinkages with an eccentric formation of core and sheath in which the sheath of the filament is a homo-polyamide and the core a copolyether amide, which has been produced by polycondensation of adipic acid with 75 to 20 mol tfo of an ether diamine of the formula: H2 - (CH2)3 - R - (CH2)3 - NH2 in which R represents either -0-, or -0-(CH2)n -Clin which n is 2-4, and 25 to SO mol % of hexamethylene diamine.

2. A composite filament as claimed in claim 1 in which 50 to 40 mol of the ether diamine is employed in producing the copolyether amide,

3. » A composite filament as claimed in claim 1 or claim 2 in which 50 to 60 mol % of hexamethylene diamine is employed in producing the copolyether amide,

4. A composite filament as claimed in Any of claims 1-3 in which the ether diamine used in the preparation of the copolyether amide is of the formul :- H2N " (CH2)3 - 0 ~ (CH2)2 " 0 " (CH2^3 " NH2

5. A composite filament as claimed in any of claims 1-4 in which the sheath is polyhexamethylene adipamide.

6. A composite filament as claimed in any of claims 1-4 in the sheath .is polycaprolactam.

7. A composite filament as claimed in any of claims 1-6 in which the ratio by weight between sheath and core is between 30:70 and 70:30. S. A composite filament, as claimed in claim 1, substantially as herein described with reference to the Examples , For the Applicants